Android sync errors - Internal server error

I am trying to use server based offline maps to do all my edits offline and sync them to the server online. I am able to do all my edits usccessfully. However, when I am doing sync using the geodatabaseSyncTask.syncGeodatabase() call, everytime I see, "Internal Server Error".

Can somebody let me know if this is an issue at my end or the service end?

You can try using a network traffic tool like fiddler to capture the request that is sent to the server and then inspect the url and the parameters of this request in case something is wrong or missing. Another thing would be to try using the Esri offline sample at arcgis-runtime-samples-android/OfflineEditor at master · Esri/arcgis-runtime-samples-android · GitHub with your service. If your service works with the Esri sample, then it looks like something is wrong in your code end. If the service still fails, it is most likely a service issue.